Hello,
I am experiencing a severe performance and responsiveness issue with a
Windows Server 2025 VM running on Proxmox VE 9.2.
The issue is reproducible and the comparison with Windows Server 2022 is
very clear.
I created a fresh Windows Server 2022 VM on the SAME physical Proxmox host,
using the same storage, similar virtual hardware and the same CPU/RAM
resources.
Windows Server 2022 is extremely responsive, while Windows Server 2025 is
noticeably slow and sluggish.
HOST
----
Physical CPU:
Intel Xeon E5-2620 v4
Proxmox VE:
9.2.0
PVE Manager:
9.2.5
Kernel:
7.0.14-8-pve
QEMU:
11.0.2-2
Storage:
HP Smart Array H240 controller with local-lvm storage.
WINDOWS SERVER 2025 VM
----------------------
- 8 vCPU
- 12 GB RAM
- 1 socket
- NUMA disabled
- CPU type: host
- OVMF
- Q35
- VirtIO network
- 180 GB disk
- TPM 2.0
- QEMU Guest Agent enabled
The VM is noticeably sluggish during normal use, including the Windows
desktop and basic administrative tasks.
The issue was present from the initial VM configuration.
TESTS PERFORMED ON WINDOWS SERVER 2025
---------------------------------------
We tested multiple virtual CPU models:
- host
- x86-64-v2-AES
- x86-64-v3
The performance issue persisted with all of them.
We also tested different VirtIO SCSI controller configurations.
The VM was initially configured with VirtIO SCSI Single, and the
performance problem was already present.
During troubleshooting, the SCSI controller was changed to VirtIO SCSI
(non-single), but the performance issue persisted.
Therefore, changing the SCSI controller did not resolve the problem.
WINDOWS SERVER 2022 CONTROL TEST
---------------------------------
We created a fresh Windows Server 2022 VM on the same physical Proxmox
host.
Configuration:
- 8 vCPU
- 12 GB RAM
- 1 socket
- NUMA disabled
- CPU type: host
- OVMF
- Q35
- VirtIO network
- 180 GB disk
- TPM 2.0
- QEMU Guest Agent enabled
- VirtIO SCSI Single
Windows Server 2022 is extremely responsive.
We then configured a static IP and DNS, rebooted the VM, and joined it to
our existing Active Directory domain.
It remained extremely responsive after joining the domain.
We then installed AD DS and promoted the Server 2022 VM as a second
domain controller.
DNS and Global Catalog were enabled.
After the promotion, the Server 2022 VM remained extremely responsive.
ACTIVE DIRECTORY HEALTH
-----------------------
The existing domain controller is:
DC01.example.local
10.10.10.10
The new Windows Server 2022 domain controller is:
DC02.example.local
10.20.20.20
Replication is healthy:
repadmin /replsummary
- DC01: 0/5 errors
- DC02: 0/5 errors
dcdiag:
- Connectivity: PASS
- Advertising: PASS
- NetLogons: PASS
- Replications: PASS
DNS SRV records correctly advertise both domain controllers.
The Server 2022 VM also shows approximately 0.1% system interrupts during
normal operation.
Therefore, the issue does not appear to be caused by Active Directory,
DNS, domain membership, or the fact that the VM is running as a domain
controller.
IMPORTANT OBSERVATION
---------------------
The most important observation is:
Windows Server 2022:
- Same physical Proxmox host
- Same storage
- Same CPU generation
- Same 8 vCPU allocation
- Same 12 GB RAM allocation
- Same OVMF/Q35 configuration
- Same VirtIO networking
- Joined to the domain
- Promoted to a domain controller
- Extremely responsive
Windows Server 2025:
- Same physical Proxmox host
- Same storage
- Same CPU generation
- Same 8 vCPU allocation
- Same 12 GB RAM allocation
- OVMF/Q35
- VirtIO networking
- Significantly slower / sluggish
- CPU models host, x86-64-v2-AES and x86-64-v3 tested without resolving
- Different VirtIO SCSI configurations tested without resolving
WINDOWS SERVER 2025 VM CONFIGURATION
-------------------------------------
The relevant VM configuration is:
agent: 1
bios: ovmf
cores: 8
cpu: host
machine: pc-q35-11.0+pve2
memory: 12288
net0: virtio=<REDACTED-MAC>,bridge=vmbr0,firewall=1
numa: 0
ostype: win11
scsi0: local-lvm:vm-105-disk-1,size=180G
scsihw: virtio-scsi-pci
sockets: 1
tpmstate0: local-lvm:vm-105-disk-2,size=4M,version=v2.0
vga: std
WINDOWS SERVER 2022 VM CONFIGURATION
-------------------------------------
The relevant VM configuration is:
agent: 1
bios: ovmf
cores: 8
cpu: host
machine: pc-q35-11.0+pve2
memory: 12288
net0: virtio=<REDACTED-MAC>,bridge=vmbr0,firewall=1
numa: 0
ostype: win11
scsi0: local-lvm:vm-106-disk-1,discard=on,iothread=1,size=180G
scsihw: virtio-scsi-single
sockets: 1
tpmstate0: local-lvm:vm-106-disk-2,size=4M,version=v2.0
vga: std
PVE VERSION
-----------
proxmox-ve: 9.2.0 (running kernel: 7.0.14-8-pve)
pve-manager: 9.2.5
proxmox-kernel-7.0.14-8-pve-signed: 7.0.14-8
pve-qemu-kvm: 11.0.2-2
qemu-server: 9.2.1
QUESTION
--------
Has anyone experienced similar Windows Server 2025 performance or
responsiveness issues with Proxmox VE 9.2 / QEMU 11?
Could this be related to Windows Server 2025 compatibility with the
current kernel, QEMU or virtualization environment?
We have already tested different CPU models and different VirtIO SCSI
configurations, without resolving the problem.
We would appreciate any recommended troubleshooting steps, known
workarounds, or specific VM configuration recommendations for Windows
Server 2025 on PVE 9.2.
Thank you.
I am experiencing a severe performance and responsiveness issue with a
Windows Server 2025 VM running on Proxmox VE 9.2.
The issue is reproducible and the comparison with Windows Server 2022 is
very clear.
I created a fresh Windows Server 2022 VM on the SAME physical Proxmox host,
using the same storage, similar virtual hardware and the same CPU/RAM
resources.
Windows Server 2022 is extremely responsive, while Windows Server 2025 is
noticeably slow and sluggish.
HOST
----
Physical CPU:
Intel Xeon E5-2620 v4
Proxmox VE:
9.2.0
PVE Manager:
9.2.5
Kernel:
7.0.14-8-pve
QEMU:
11.0.2-2
Storage:
HP Smart Array H240 controller with local-lvm storage.
WINDOWS SERVER 2025 VM
----------------------
- 8 vCPU
- 12 GB RAM
- 1 socket
- NUMA disabled
- CPU type: host
- OVMF
- Q35
- VirtIO network
- 180 GB disk
- TPM 2.0
- QEMU Guest Agent enabled
The VM is noticeably sluggish during normal use, including the Windows
desktop and basic administrative tasks.
The issue was present from the initial VM configuration.
TESTS PERFORMED ON WINDOWS SERVER 2025
---------------------------------------
We tested multiple virtual CPU models:
- host
- x86-64-v2-AES
- x86-64-v3
The performance issue persisted with all of them.
We also tested different VirtIO SCSI controller configurations.
The VM was initially configured with VirtIO SCSI Single, and the
performance problem was already present.
During troubleshooting, the SCSI controller was changed to VirtIO SCSI
(non-single), but the performance issue persisted.
Therefore, changing the SCSI controller did not resolve the problem.
WINDOWS SERVER 2022 CONTROL TEST
---------------------------------
We created a fresh Windows Server 2022 VM on the same physical Proxmox
host.
Configuration:
- 8 vCPU
- 12 GB RAM
- 1 socket
- NUMA disabled
- CPU type: host
- OVMF
- Q35
- VirtIO network
- 180 GB disk
- TPM 2.0
- QEMU Guest Agent enabled
- VirtIO SCSI Single
Windows Server 2022 is extremely responsive.
We then configured a static IP and DNS, rebooted the VM, and joined it to
our existing Active Directory domain.
It remained extremely responsive after joining the domain.
We then installed AD DS and promoted the Server 2022 VM as a second
domain controller.
DNS and Global Catalog were enabled.
After the promotion, the Server 2022 VM remained extremely responsive.
ACTIVE DIRECTORY HEALTH
-----------------------
The existing domain controller is:
DC01.example.local
10.10.10.10
The new Windows Server 2022 domain controller is:
DC02.example.local
10.20.20.20
Replication is healthy:
repadmin /replsummary
- DC01: 0/5 errors
- DC02: 0/5 errors
dcdiag:
- Connectivity: PASS
- Advertising: PASS
- NetLogons: PASS
- Replications: PASS
DNS SRV records correctly advertise both domain controllers.
The Server 2022 VM also shows approximately 0.1% system interrupts during
normal operation.
Therefore, the issue does not appear to be caused by Active Directory,
DNS, domain membership, or the fact that the VM is running as a domain
controller.
IMPORTANT OBSERVATION
---------------------
The most important observation is:
Windows Server 2022:
- Same physical Proxmox host
- Same storage
- Same CPU generation
- Same 8 vCPU allocation
- Same 12 GB RAM allocation
- Same OVMF/Q35 configuration
- Same VirtIO networking
- Joined to the domain
- Promoted to a domain controller
- Extremely responsive
Windows Server 2025:
- Same physical Proxmox host
- Same storage
- Same CPU generation
- Same 8 vCPU allocation
- Same 12 GB RAM allocation
- OVMF/Q35
- VirtIO networking
- Significantly slower / sluggish
- CPU models host, x86-64-v2-AES and x86-64-v3 tested without resolving
- Different VirtIO SCSI configurations tested without resolving
WINDOWS SERVER 2025 VM CONFIGURATION
-------------------------------------
The relevant VM configuration is:
agent: 1
bios: ovmf
cores: 8
cpu: host
machine: pc-q35-11.0+pve2
memory: 12288
net0: virtio=<REDACTED-MAC>,bridge=vmbr0,firewall=1
numa: 0
ostype: win11
scsi0: local-lvm:vm-105-disk-1,size=180G
scsihw: virtio-scsi-pci
sockets: 1
tpmstate0: local-lvm:vm-105-disk-2,size=4M,version=v2.0
vga: std
WINDOWS SERVER 2022 VM CONFIGURATION
-------------------------------------
The relevant VM configuration is:
agent: 1
bios: ovmf
cores: 8
cpu: host
machine: pc-q35-11.0+pve2
memory: 12288
net0: virtio=<REDACTED-MAC>,bridge=vmbr0,firewall=1
numa: 0
ostype: win11
scsi0: local-lvm:vm-106-disk-1,discard=on,iothread=1,size=180G
scsihw: virtio-scsi-single
sockets: 1
tpmstate0: local-lvm:vm-106-disk-2,size=4M,version=v2.0
vga: std
PVE VERSION
-----------
proxmox-ve: 9.2.0 (running kernel: 7.0.14-8-pve)
pve-manager: 9.2.5
proxmox-kernel-7.0.14-8-pve-signed: 7.0.14-8
pve-qemu-kvm: 11.0.2-2
qemu-server: 9.2.1
QUESTION
--------
Has anyone experienced similar Windows Server 2025 performance or
responsiveness issues with Proxmox VE 9.2 / QEMU 11?
Could this be related to Windows Server 2025 compatibility with the
current kernel, QEMU or virtualization environment?
We have already tested different CPU models and different VirtIO SCSI
configurations, without resolving the problem.
We would appreciate any recommended troubleshooting steps, known
workarounds, or specific VM configuration recommendations for Windows
Server 2025 on PVE 9.2.
Thank you.